scholarly journals Mycorrhiza Regulates Signal Substance Levels and Pathogen Defense Gene Expression to Resist Citrus Canker

2019 ◽  
Vol 47 (4) ◽  
pp. 1161-1167 ◽  
Author(s):  
Miao-Miao XIE ◽  
Yi-Can ZHANG ◽  
Li-Ping LIU ◽  
Ying-Ning ZOU ◽  
Qiang-Sheng WU ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Citrus Canker ◽  
Poncirus Trifoliata ◽  
Digital Object Identifier ◽  
Pathogen Defense ◽  
Gene Expressions ◽  
Defense Gene Expression ◽  
Defense Gene

Citrus canker is a quarantined disease, severely harming citrus plants. Soil beneficial arbuscular mycorrhizal fungi (AMF) can provide a biological control pathway to resist pathogens. This work was to test changes of signal substances including hydrogen peroxide (H2O2), nitric oxide (NO), calmodulin (CaM), salicylic acid (SA) and jasmonic acid (JA) and the pathogen defense gene expression in roots of AMF (Paraglomus occultum) and non-AMF trifoliate orange (Poncirus trifoliata) seedlings after infected by a expressions citrus canker pathogen (Xanthomonas axonopodis pv. Citri, Xac). AMF inoculation significantly improved plant height, stem diameter and leaf number. Xac infection dramatically decreased root H2O2, NO, and SA levels, but increased root CaM and JA concentrations in non-AMF seedlings. There were higher H2O2 and CaM levels and lower JA levels in Xac-infected seedlings than in non-Xac-infected seedlings under mycorrhization. Under non-Xac infection, mycorrhizal treatment reduced root H2O2, NO, and SA but increased CaM and JA levels. However, under Xac infection, mycorrhizal inoculation distinctly accelerated root H2O2, NO, CaM, and SA accumulation, accompanied with up-regulated expression levels of root PtEPS1 (enhance pseudomonas susceptibility 1) and PtPR4 (pathogenesis related gene 4), indicating that Xac stimulated mycorrhizal roles in enhancing resistance of citrus canker. Such results imply that citrus plants with pre-inoculated AMF had stronger resistance to Xac infection through increasing signal substrate accumulation and pathogen defense gene expressions.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

scholarly journals Community Analysis of Arbuscular Mycorrhizal Fungi in Roots ofPoncirus trifoliataandCitrus reticulataBased on SSU rDNA

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Peng Wang ◽  
Yin Wang
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Glomus Intraradices ◽  
Arbuscular Mycorrhizal ◽  
Small Subunit ◽  
Poncirus Trifoliata ◽  
Spore Density ◽  
Morphological Observation ◽  
Trifoliate Orange ◽  
Hyphal Length

Morphological observation of arbuscular mycorrhizal fungi (AMF) species in rhizospheric soil could not accurately reflect the actual AMF colonizing status in roots, while molecular identification of indigenous AMF colonizing citrus rootstocks at present was rare in China. In our study, community of AMF colonizing trifoliate orange (Poncirus trifoliataL. Raf.) and red tangerine (Citrus reticulataBlanco) were analyzed based on small subunit of ribosomal DNA genes. Morphological observation showed that arbuscular mycorrhizal (AM) colonization, spore density, and hyphal length did not differ significantly between two rootstocks. Phylogenetic analysis showed that 173 screened AMF sequences clustered in at least 10 discrete groups (GLO1~GLO10), all belonging to the genus ofGlomusSensu Lato. Among them, GLO1 clade (clustering with uncultured Glomus) accounting for 54.43% clones was the most common in trifoliate orange roots, while GLO6 clade (clustering withGlomus intraradices) accounting for 35.00% clones was the most common in red tangerine roots. Although, Shannon-Wiener indices exhibited no notable differences between both rootstocks, relative proportions of observed clades analysis revealed that composition of AMF communities colonizing two rootstocks varied severely. The results indicated that native AMF species in citrus rhizosphere had diverse colonization potential between two different rootstocks in the present orchards.

scholarly journals HOS15 is a transcriptional corepressor of NPR1-mediated gene activation of plant immunity

2020 ◽  
Vol 117 (48) ◽  
pp. 30805-30815
Author(s):  
Mingzhe Shen ◽  
Chae Jin Lim ◽  
Junghoon Park ◽  
Jeong Eun Kim ◽  
Dongwon Baek ◽  
...  
Keyword(s):  
Gene Expression ◽  
Ubiquitin Ligase ◽  
Transcriptional Activation ◽  
Plant Immunity ◽  
Gene Activation ◽  
Transcriptional Corepressor ◽  
Defense Gene Expression ◽  
Dynamic Regulation ◽  
Defense Gene ◽  
Transcriptional Corepressors

Transcriptional regulation is a complex and pivotal process in living cells. HOS15 is a transcriptional corepressor. Although transcriptional repressors generally have been associated with inactive genes, increasing evidence indicates that, through poorly understood mechanisms, transcriptional corepressors also associate with actively transcribed genes. Here, we show that HOS15 is the substrate receptor for an SCF/CUL1 E3 ubiquitin ligase complex (SCFHOS15) that negatively regulates plant immunity by destabilizing transcriptional activation complexes containing NPR1 and associated transcriptional activators. In unchallenged conditions, HOS15 continuously eliminates NPR1 to prevent inappropriate defense gene expression. Upon defense activation, HOS15 preferentially associates with phosphorylated NPR1 to stimulate rapid degradation of transcriptionally active NPR1 and thus limit the extent of defense gene expression. Our findings indicate that HOS15-mediated ubiquitination and elimination of NPR1 produce effects contrary to those of CUL3-containing ubiquitin ligase that coactivate defense gene expression. Thus, HOS15 plays a key role in the dynamic regulation of pre- and postactivation host defense.

scholarly journals Characterization of a Diffusible Signal Capable of Inducing Defense Gene Expression in Tobacco

1997 ◽  
Vol 113 (2) ◽  
pp. 621-629 ◽  
Author(s):  
J. Chappell ◽  
A. Levine ◽  
R. Tenhaken ◽  
M. Lusso ◽  
C. Lamb
Keyword(s):  
Gene Expression ◽  
Defense Gene Expression ◽  
Defense Gene

scholarly journals Enhancement of Drought Tolerance in Trifoliate Orange by Mycorrhiza: Changes in Root Sucrose and Proline Metabolisms

2018 ◽  
Vol 46 (1) ◽  
pp. 270-276 ◽  
Author(s):  
Fei ZHANG ◽  
Jia-Dong HE ◽  
Qiu-Dan NI ◽  
Qiang-Sheng WU ◽  
Ying-Ning ZOU
Keyword(s):  
Drought Tolerance ◽  
Mycorrhizal Fungi ◽  
Water Status ◽  
Lateral Roots ◽  
Arbuscular Mycorrhizal ◽  
Dry Weight ◽  
Sucrose Phosphate Synthase ◽  
Poncirus Trifoliata ◽  
Trifoliate Orange ◽  
Am Symbiosis

Sucrose and proline metabolisms are often associated with drought tolerance of plants. This study was conducted to investigate the effects of two arbuscular mycorrhizal fungi (AMF) species (Funneliformis mosseae and Paraglomus occultum) on root biomass, lateral root number, root sucrose and proline metabolisms in trifoliate orange (Poncirus trifoliata) seedlings under well-watered (WW) or drought stress (DS). All the AMF treatments significantly increased root dry weight, taproot length, and the number of lateral roots in 1st, 2nd, and 3rd class under WW and DS. Mycorrhizal seedlings conferred considerably higher fructose and glucose concentrations but lower sucrose accumulation, regardless of soil water status. Under DS, F. mosseae treatment significantly increased root sucrose synthase (SS, degradative direction) and sucrose phosphate synthase (SPS) activity but deceased root acid invertase (AI) and neutral invertase (NI) activity, and P. occultum inoculation markedly increased root AI, NI, SS, and SPS activities. AMF treatments led to a lower proline accumulation in roots, in company with lower activities of Δ1-pyrroline-5-carboxylate synthetase (P5CS), δ-ornithine aminotransferase (OAT), Δ1-pyrroline-5-carboxylate reductase (P5CR), and proline dehydrogenase (ProDH) in roots. It appears that the AM symbiosis induced greater root development and sucrose and proline metabolisms to adapt DS.

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